Lc. Romero et al., Salt regulation of O-acetylserine(thiol)lyase in Arabidopsis thaliana and increased tolerance in yeast, PL PHYS BIO, 39(7-8), 2001, pp. 643-647
The cytosolic isoform of O-acetylserine(thiol)lyase (OASTL, EC 4.2.99.8), t
he enzyme that catalyses cysteine biosynthesis, is induced in leaves of Ara
bidopsis thaliana exposed to salt stress. The protein level increases after
1 d sodium chloride treatment, and progressively for up to 5 d. The overex
pression in yeast of the Atcys-3A gene coding for this OASTL isoform can su
pport the growth of the yeast cells at high concentrations of sodium chlori
de, suggesting that the plant protein is able to confer salt tolerance in y
east. Besides, the O-acetylserine(thiol)lyase enzyme activity is not inhibi
ted in vitro by cations such as Li+ or Na+. Our results suggest that the pl
ant is responding to the salt stress by inducing cysteine biosynthesis as a
protection against high ion concentrations. (C) 2001 Editions scientifique
s et medicales Elsevier SAS.